In U.S. Pat. Nos. B1 5,044,852, 5,584,630 and others, fasteners are disclosed which utilize quick-setting adhesives, such as anaerobic or cyanoacrylate adhesives. The fasteners are so designed that upon pressing them against a substrate to which the fasteners are to be attached, the adhesive is automatically dispensed into the interface between the fastener and the substrate and in but moments, the fastener is securely attached to the substrate.
The adhesive is contained in a reservoir cup in the fastener. The reservoir cup is made from a material which is intended neither to react with nor promote curing of the adhesive therewithin. The remainder of the fastener is intended to bond with the adhesive as the latter cures and may be formed of a rigid plastic. Examples of suitable plastics are found in U.S. Pat. No. 5,277,530.
As stated in Ser. No. 09/123,674 in some instances the adhesive had tended to cure in the reservoir notwithstanding the non-reactive character of the reservoir cup material, particularly if the loaded reservoir cup in a fastener was stored for a long interval. For example, an adhesive such as a cyanoacrylate, must have atmospheric water vapor excluded if premature curing is to be prevented. On the other hand, if an anaerobic adhesive is used, oxygen must be present to prevent premature curing. Accordingly, studies of these problems have indicated that the water vapor in the ambient atmosphere is apparently captured in the reservoir cup at the time it is filled with the adhesive and/or the piston is inserted in the reservoir cup and such water vapor will cause premature curing of cyanoacrylate adhesives. It becomes important to include oxygen in the reservoir cup of fasteners utilizing anaerobic adhesives.
After a reservoir cup is filled with the proper amount of adhesive, a piston is inserted in the open end to seal the interior. As stated in Ser. No. 09/123,674, a hydraulic lock may occur preventing insertion of the piston into the reservoir cup which prevents the piston from properly seating in the cup. Such lock can also prevent further displacement of the piston into the cup or create a buildup of excessive pressure within the reservoir leading to a squirting out of the adhesive as the fastener is applied to a substrate to which it is to be attached.
As stated in Ser. No. 09/123,674, modifications of both the reservoir and the fastener were desirable as well as the methods of charging the reservoir cup with adhesive and inserting the piston therein. Such modified methods of charging the reservoir cup with adhesive and inserting the piston therein may be further improved. As methods are automated and production levels increase, the need to automate verification of the methods also increases. The reason is simply that manual verification methods are increasingly laborious as production levels increase. More specifically, as production levels increase, the number of verifications needed also increases. In the situation where the human eye is used to verify that the methods are performed correctly, more workers are required as production levels increase. In turn, such methods become increasingly costly.
It has been found desirable to modify the current methods of charging the reservoir cup with adhesive and inserting the piston therein in order to include an automated way of verifying the various steps of the methods and providing a cost saving system.